diff --git a/src/backend/storage/buffer/bufmgr.c b/src/backend/storage/buffer/bufmgr.c
index cf5b1e76caf..d00a60fab76 100644
--- a/src/backend/storage/buffer/bufmgr.c
+++ b/src/backend/storage/buffer/bufmgr.c
@@ -1169,10 +1169,15 @@ BufferAlloc(SMgrRelation smgr, char relpersistence, ForkNumber forkNum,
 	 * paranoia.  We also reset the usage_count since any recency of use of
 	 * the old content is no longer relevant.  (The usage_count starts out at
 	 * 1 so that the buffer can survive one clock-sweep pass.)
+	 *
+	 * Make sure BM_PERMANENT is set for buffers that must be written at every
+	 * checkpoint.  Unlogged buffers only need to be written at shutdown
+	 * checkpoints, except for their "init" forks, which need to be treated
+	 * just like permanent relations.
 	 */
 	buf->tag = newTag;
 	buf->flags &= ~(BM_VALID | BM_DIRTY | BM_JUST_DIRTIED | BM_CHECKPOINT_NEEDED | BM_IO_ERROR | BM_PERMANENT);
-	if (relpersistence == RELPERSISTENCE_PERMANENT)
+	if (relpersistence == RELPERSISTENCE_PERMANENT || forkNum == INIT_FORKNUM)
 		buf->flags |= BM_TAG_VALID | BM_PERMANENT;
 	else
 		buf->flags |= BM_TAG_VALID;
diff --git a/src/include/storage/buf_internals.h b/src/include/storage/buf_internals.h
index 521ee1cfaea..ecbcf392bc5 100644
--- a/src/include/storage/buf_internals.h
+++ b/src/include/storage/buf_internals.h
@@ -39,7 +39,7 @@
 #define BM_PIN_COUNT_WAITER		(1 << 6)		/* have waiter for sole pin */
 #define BM_CHECKPOINT_NEEDED	(1 << 7)		/* must write for checkpoint */
 #define BM_PERMANENT			(1 << 8)		/* permanent relation (not
-												 * unlogged) */
+												 * unlogged, or init fork) */
 
 typedef bits16 BufFlags;